A base member of the above-mentioned type is known, for example the base plate of a ski binding which is available on the market. In this base plate, three shoulders are provided in each individual bore, serve to hold an inserted fastening screw, and are designed along a course of the thread. The surface of each shoulder extends thereby in the direction of the course of the thread and thus has an inclination corresponding to the pitch of the thread, which assures a satisfactory holding of the individual fastening screws. The disadvantage of shoulders which are constructed in this manner is that an apparatus with special tools must be used for the manufacture of suitable thread sections. For a secure hold of the fastening screws in this holding arrangement, the use of three shoulders is absolutely necessary, which in turn requires the use of three tools. The three tools must in addition be eroded in order to be able to manufacture the necessary surface of the individual shoulders, which surface corresponds with the pitch of the thread. Furthermore, the soconstructed shoulders can easily be damaged, which endangers the secure hold and thus the vertical position of the individual fastening screws. This has the result that, due to the installation, the screws are in a position with respect to the upper side of the ski which differs from the vertical, through which a goal of the invention is no longer achieved. This goal is that a secure fastening of the base plate of a ski binding without any further manipulation only by screwing the fastening screw into the mounting, namely into the ski, is to be able to take place.
A purpose of the invention is to provide a base member of the above-mentioned type with bores designed so that the number of shoulders is reduced and their ability to hold and center the individual fastening screws prior to their use is improved, as compared with the conventional solution, whereby the stability of the shoulders which are used is supposed to be increased and their design is supposed to be simplified.